Visual Illusions

Category archives for Visual Illusions

UPDATE: I’ve messed with some of the images below the fold, which will hopefully make it easier for people to see the illusion without having to move all round the room. Last year, Rob Jenkins published a seriously spooky-looking illusion (it freaks my son out) in the journal Perception (1). Take a look at this…

One of my favorite optical illusions is the rotating face, an instance of depth inversion. I like it so much that I sometimes use the above image as my avatar around the web. If you’re not familiar with the illusion, what you’re seeing is a 3D mask, one side of which is convex, while the…

I love afterimages and aftereffects, so I was excited to see that the 2008 winner for Best Illusion of the Year is a new afterimage illusion. To see the illusion for your self, watch this sequence of images for about 30 seconds (it takes at least 30 seconds for it to really work for me):…

I frequently hear people imply, if they don’t state directly, that two working eyes are required for depth perception. This is surprising because with a moment’s reflection, it’s easy to see that there are depth cues that don’t require both eyes. In fact, out of the many, many cues to depth that our visual system…

From Anstis & Casco, 2006, Movie 1, p. 1088 OK, here’s a really, really cool illusion published last year, and that I learned about only recently. To see it, go to Stuart Anstis’ page here, watch the first movie only, and then come back here. You should have seen two flies moving in circles with…

Everybody knows the Margaret Thatcher Illusion. If you’ve forgotten about it, here’s the best example I’ve found (from Schwaninger et al.1) Both the top and bottom pairs are the same photos, but they look very different depending on whether they’re upright or inverted. In the top pair (the inverted ones), the face on the left…

Everybody’s seen Kanizsa’s triangle: It’s a simple illusory figure illusion, first reported by Kanizsa(1). The illusion is likely caused by the processes that the visual system uses to separate figures from their ground(2), but to date there doesn’t appear to be any consensus about exactly how these processes cause the perception of illusory figures (here’s…

In honor of the announcement of the Best Visual Illusion of the Year (via Steve), I thought I’d revive the old cool visual illusion series. I may post about this year’s winner, the leaning tower illusion, in the future, but I just now read the paper, so I have some work to do first. Instead,…

One of my favorite perceptual illusions isn’t actually visual. It’s often called the “cutaneous rabbit” illusion1, for reasons that will be apparent in a moment. I stumbled across it when reading a paper by Dennett and Kinsbourne2. Here’s their description of the illusion (p. 188): The subject’s arm rests cushioned on a table, and mechanical…